Micrometer



June 15, 1943. E, c, SHQEMAKER 2,322,167

MI CROMETER Filed Sept. 19, 1942 2 Sheets-Shet 1 Emory 6! Shaemaifler B] 2mm June 15, 1943. E. c. SHOEMAKER 2,322,157

MICROMETER v Filed Sept. 19, 1942 2 Sheets-Sheet 2 Inventor 7 Envy 63 Shoemaker Patented June 15, 1943 UNETED ST.

were? My invention relates to improvements in mi.- crometers, the principal object in view being to provide a simply constructed, accurate, easily operated device of this character adapted for extension to vary its size so that micrometers of different sizes may be rendered available in one unitary instrument.

Other and subordinate objects are also comprehended by my invention, all of which, together with the precise nature of my improvements, will be readily understood when the succeeding description and claims are read with reference to the drawings accompanying and forming part of this specification.

In said drawings:

Figure 1 is a view in side elevation of my imimproved micrometer in its preferred embodiment,

Figure 2 is a View in top plan,

Figure 3 is a view in bottom plan,

Figure 4 is a view in longitudinal section taken on the line 44 of Figure 2 and drawn to an enlarged scale,

Figure 5 is a view in transverse section taken on the line 5-5 of Figure 4,

Figure 6 is a similar view taken on the line 66 of Figure 4, and

Figure 7 is a fragmentary view in side elevation of the barrel, sleeve, and hood.

Referring to the drawings by numerals, the basic element of my improved micrometer is a bar-like beam I having a front, cylindrical, longitudinally ribbed end 2 fitted and secured in a socketed inner end 3 of a laterally extending, suitably curved anvil carrying arm 4 having a longitudinally ribbed, elongated anvil 5 suitably secured in a socketed outer end thereof to extend out of said socketed end parallel with the beam I.

Slidable on the beam I into difierent set positions is a second spindle carrying arm 6 extending laterally from one and the same side of said beam I as the anvil carrying arm 4. suitable distance from the end 2 thereof, the beam I is of substantially semi-circular cross section throughout the remainder of its length to provide a flat, opposite, bottom side 1 thereon for a purpose presently seen. The second arm 6 is provided with a transverse socket 8 in the inner end thereof, also semi-circular, to fit over the semi-circular portion of said beam I.

Extending laterally through the outer end of the second arm 6, coaxially with the anvil 5 is a measuring spindle 9 having a measuring end II) From a opposed to the anvil 5 on one side of said arm 6. The other end of the spindle 9 is longitudinally ribbed, as at I2, and fitted in a complemental socket I 3 of a sleeve I i provided with a knurled hand grip, outer end I5 for turning said spindle 9.

The sleeve It; is designed for a working fit in a barrel I6 secured at one end in one sideof the second arm 5 concentrically of the spindle 9 and sleeve It. The sleeve I4 is calibrated around its inner end, as at I6, in, one-thousandths of an inch numbered from zero upwardly successively. The barrel I6 is calibrated, as at IT, along one side thereof for the required length scale, with equi-distant calibrations from zero to I, said calibrations being divided into four equal sub-calibrations. The spindle I is threaded, as at I8, with the proper pitch micrometer threads into a correction thimble I9 threaded, in turn, through a housing bushing 29 set into a suitable socket 2| provided in the outer end of the second arm 6. One end of the correction thimble I9 is provided, as at 22, with grooves for a spanner wrench so that the thimble may be easily adjusted. The barrel I6 is slotted longitudinally, as at 23, and the calibrations Il extend along one side of said slot.

As the sleeve I4 rotates and moves forwardly in the barrel I5, the calibrations on said sleeve and barrel register as the spindle 9 is set toward the anvil 5 to give the correct measurement readings. For instance, the calibrations are so arranged that when zero on the sleeve I i coincides with the first marking to the right of Zero on the barrel I8, the reading will be .025 inches. The housing I8 is provided for turning to correctly set the spindle I9 in case of wear between the threads on the spindle and in the bushing I9.

On the side of the second arm 6, opposite to the arm 4, an arched guard bar 24 extends from the outer end of said arm 6 to the beam I in a common plane with the arms 4 and 6, and which serves in one capacity as a protector for the sleeve I4 and barrel I6. One end of the guard bar 24 is fitted over the outer end of the second arm 6 and the socket 29 in said arm and secured in place by screws, as at 25, extending into the correction thimble I9. The other end of the guard bar 24 is socketed, as at 26, to slidably fit over the beam I and provided on the flat side of said beam I with a Worm housing 27 containing a worm 28 fast on a shaft 29 journaled in the housing parallel with the beam I and provided with a knurled operating head 30. The worm 28 meshes with suitable teeth 3| on the flat, bottom side of the beam I.

By grasping the guard bar 24 and operating the worm 28, the beam I and anvil carrying arm 4 may be adjusted relative to the spindle carrying second arm 6 and parts carried thereby into different set positions to extend the micrometer and vary its size.

Beginning at a suitable distance from the end 2 of the beam I, said beam is provided on its flat, bottom side I with longitudinally spaced, conical sockets 32 therein spaced one inch apart and for seating a pointed set screw 33 threaded into the inner end of said second arm 6 and having a knurled head 34. A suitable lock nut 35 is provided in a recess 36 in said second arm 6 for looking said set screw 33.

As will now be seen, by means of the sockets 32 and set screw 33, the beam I may be set, together with the anvil 5, relative to the measuring spindle 9 to vary the size of the micrometer by inches.

An extensible turnbuckle-type shaft 36 is threaded at its opposite ends into the inner end of said second arm 6 and the worm housing 21, parallel with the beam I, and on the flat side of said beam, for adjustment to exert pressure against said housing in case the worm 28 should bind in the teeth 3 I, so that such binding may be easily cured.

Fitted over the slot 23 and the barrel I6 is a transversely arcuate hood 31 of suitable magnifying structure and material and having inside flanges 38 fitting against the sides of the slot 23 to prevent circumferential displacement of said hood, and provided with edge legs 39 for clasping around the barrel l6. The hood 3'! is designed to facilitate reading of the micrometer in a manner which will be clear.

The foregoing will, it is believed, sufiice to impart a clear understanding of my invention without further explanation.

Manifestly, the invention, as described, is susceptible of modification Without departing from the inventive concept, and right is herein reserved to such modifications as fall within the scope of the appended claims.

What I claim is:

1. A micrometer comprising a bar-like beam, an anvil carrying arm extending laterally from one end of said beam to one side thereof and having a cylindrical anvil fixed therein parallel with said beam, a second arm extending laterally from said beam on the same side thereof and 0pposite the first-mentioned arm, a threaded measuring spindle mounted in said second arm coaxially with said anvil and for turning toward and from the same, said beam and second arm being slidably connected for relative adjustment to space the measuring spindle from the anvil into different set positions, an arched guard bar for the spindle extending from said second arm tosaid beam, and means to relatively adjust said beam and second bar comprising a worm mounted on said guard bar, and teeth on said beam with which the worm meshes.

2. A micrometer comprising a bar-like beam, an anvil carrying arm extending laterally from one end of said beam to one side thereof and having a cylindrical anvil fixed therein parallel with said beam, a second arm extending laterally from said beam on the same side thereof and opposite the first-mentioned arm, a threaded measuring spindle mounted in said second arm c0- axially with said anvil and for turning toward and from the same, said beam and second arm being slidably connected for relative adjustment to space the measuring spindle from the anvil into different set positions, an arched guard bar for the spindle extending from said second arm to said beam, means to relatively adjust said beam and second bar comprising a worm mounted on said guard bar, and teeth on said beam with which the Worm meshes, and means to exert tension against said guard bar to prevent the worm from binding in said teeth.

EMORY C. SHOEMAKER. 

